On the verge of a billiondollar development, this Swiss secret is about to go big-time.

Switzerland’s Glacier Express might be both the world’s most scenic ski train and its most rewarding. At one terminus lies sun-kissed St. Moritz, with its immaculate pistes and infusion of ritz. At the other lies iconic Zermatt, a car-free cosmopolitan ski resort with Old Swiss flavor at the foot of the Matterhorn. In between sprawls 180 miles of the Swiss Alps­—dreamy villages, spiral train tunnels and precipitous railway viaducts. Not bad, as ski trains go. But for passionate skiers, yet another prize lurks along the route: little-known, snow-rich Andermatt.